# Linear Momentum in Collisions

### Goal: To investigate the Law of Conservation of Linear Momentum in collisions

Simulation Used: Collision Lab from the PhET at the University of Colorado.
• Theory
• Preliminary Settings.
• Open the simulation Collision Lab.
• From the menu on the right, select: Show Values
• In the yellow window below, click on "More Data"

• Activity 1: Elastic Collisions in one dimension. Ball 2 is initially at rest.
• On the menu to the right, slide the indicator all the way to the right for a perfectly elastic collision.
• For the given masses and initial speeds of the two balls, determine the velocity and momentum after the collision.

 Ball Mass (kg) Before the Collision After the Collision V (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2
• Question: Is the momentum conserved?
• Question: Is the energy conserved?

• Activity 2: Elastic Collisions in one dimension. Balls 1 and 2 initially moving in the same direction.
• Ball 1 and Ball 2 initially moving in the same direction

•  Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2
• Question: Is the momentum conserved?
• Question: Is the energy conserved?

• Activity 2: Elastic Collisions in one dimension. Balls 1 and 2 initially moving in the opposite direction.

• Note that when Ball 2 moves opposite to Ball 1, its velocity and momentum are negative!

•  Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2
• Question: Is the momentum conserved?
• Question: Is the energy conserved?

• Activity 3: Inelastic Collisions

• On the menu to the left, slide the indicator all the way to the left to ensure perferctly inelastic collision.

•  Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2

 Ball Mass (kg) Before the Collision After the Collision v (m/s) Momentum (kg.m/s) v (m/s) Momentum (kg.m/s) 1 2
• Question: Is the momentum conserved?
• Question: Is the energy conserved?

Acknowledgements.
• The Java Applet comes from the PhET Interactive Simulations at the University of Colorado, Boulder.
• Some activities are based on the "Laboratory Manual, Physics 231 - 232" by Walter Wimbush, Northern Virginia Community College, 2008.

Created: Tue Oct 16 11:32:17 Eastern Daylight Time 2012 Last modified: Tue Oct 16 13:01:59 EDT 2012